The worldwide software industry is gradually moving to a new paradigm of development where object modeling is moving from being just an analysis/design aid to being a more pervasive end-to-end system development tool. This new paradigm views modeling and coding on a continuum with more components being traversed from the domain of coding to the domain of modeling. This shift has been facilitated by the emergence of various modeling standards like Unified Modeling Language (UML), Meta Object Facility (MOF), Extended Markup Language (XML), and so on. There are ongoing development efforts to make such facilities semantically richer.
When modeling takes over the space of coding, it must contend with the problems of size, change, and variation just as coding does now. To manage the complexity of size, information systems are partitioned into separate modules or components that interact with each other. During system development, these components are assigned to team members who work on them in parallel using independent workspaces (configurations). These independent workspaces are then consolidated or merged into a baseline workspace through a process known as ‘diff & merge’. Diff & merge essentially involves comparison of two workspaces and reconciling the differences by copying and/or deleting appropriate elements from one workspace to the other. Diff & merge is a complex process fraught with risks if not performed carefully. It has occurred to the inventor that the process would be greatly enhanced if a tool were available that could meet the conditions stated below.
Firstly, a proposed tool must present differences between parallel workspaces in a structured manner that makes semantic sense to a user. Additionally, the difference-presentation structure should reflect the structure of the model.
Secondly, a proposed tool should have a capability of keeping the difference presentation updated dynamically as the differences are reconciled incrementally. This requirement is critical, especially in a model repository, where model elements are typically connected up in a graph-like structure. When a model element is modified during the merge process, the differences should be recomputed for all the impacted elements. If this were not done, difference presentation would be inaccurate, leading to incorrect merge operations.
Thirdly, in the case of extensible model repository systems, a proposed tool should enable end-users to specify a structure for difference computation for any model elements that are user-introduced.
Most commercial repository systems do not provide any built-in tool support for workspace level diff and merge capability. Instead, they provide object-level support for detecting conflicts when an object is checked into a baseline. In this case, a user must manually compare the two differing object versions and then manually reconcile the differences.
Systems that do provide built-in support for diff and merge only do so for pre-defined, standard meta models such as UML models or ER models. There is as yet in prior or current art no provision for extending diff and merge capabilities to user-enhanced meta models. There is no known system that can satisfy the three desires stated above.
Therefore, what is clearly needed is a software tool supported by algorithm that can provide diff and merge capability such that the three conditions stated above are satisfied.